Field of the Invention
The present invention relates to a fluid level activated electrical switch and more particularly to a float switch for use in conjunction with a controller to automatically restore or drain fluid to a desired level by supplying power to a pump motor or a solenoid operated valve.
Switches responsive to fluid levels have utilized a variety of approaches for opening and closing an electrical circuit. Fluid level switch devices usually incorporate a float buoy for sensing the fluid level, the float buoy being operatively connected to a switch device. Mercury switches provide excellent switching characteristics and are readily adaptable to fluid level actuated float switches. They usually consist of a sealed glass tube of mercury into which a pair of electrodes extend. When tipped at a predetermined angle, the mercury will travel through the tube to bridge a gap between the two electrodes to actuate the switch. However, mercury is a hazardous material and there has been movement away from its use in float switches, especially where breakage of the glass tube is possible.
One alternative to a mercury-switch based float switch has been to replace the mercury tube with an enclosed raceway containing a conductive sphere. The sphere travels through the raceway as the float buoy moving up and down according to the fluid level tips the switch member. The sphere will contact an arm or yoke which will activate or deactivate the load, as disclosed in U.S. Pat. No. 5,087,801 to Johnston, U.S. Pat. No. 3,944,770 to Pepper, U.S. Pat. No. 4,592,576 to Frede, U.S. Pat. No. 4,644,117 to Grimes her conductive spheres contact conductive strips etched onto the raceway such as disclosed in U.S. Pat. No. 3,733,447 to Schneider, Jr.
A problem arises when the fluid levels monitored do not change uniformly. Wave action, for example, may cause prior art devices to switch on and off frequently and erratically causing burn out of the attached motors.
Therefore, what is needed is a fluid level responsive electrical float switch which does not subject the motor to erratic energization, a cause of burnout The present invention solves this problem by providing a conductive ball to make a direct contact with conductive switch contacts in three different positions, one of which is a neutral, intermediate position, within a fluid level activated float switch. The neutral intermediate position of the present invention operates as a delay mechanism which prevents wave action in the fluid from turning on and off the load.